Description

SH89330 Heavy Duty Electric Motor

Efficiency

In terms of power efficiency, DC motors generally have the advantage, as permanent magnets are more efficient than electromagnets. Brushless DC motors are even more efficient since they have no friction from brushes or slip rings pressing against the rotor or power losses from brush arcing.

By comparison, AC induction motors have significantly lower efficiency, with power losses mainly occurring in heat produced in the windings during induction. The difference can be as much as 30%, making DC motors far more suited for applications where power must be strictly managed.

Size

An electric motor’s allowable size may be limited by the available mounting space, especially when the motor, gearbox, and load are fitted inside a small package. Generally speaking, DC brushed and brushless motors offer a higher power density than AC motors, especially for sub-horsepower applications. Universal motors also offer a very high power density for high-speed applications such as power tools and home appliances.

Maintenance

The maintenance required for a motor and the time and effort required to carry it out greatly impact the motor’s total cost of ownership. For DC motors, the primary maintenance requirement is for the changing of brushes, which typically wear out over several thousand hours or less, depending on how the motor is operated. While this is not a task that frequently occurs, removing and disassembling the motor can be difficult and costly, resulting in a significant amount of lost productivity in applications that are always ‘on.’

AC motors are generally more reliable with low maintenance requirements, and their service life is often limited only by the bearing life. Because they do not need commutators, brushes, or slip rings, they don’t have parts that wear out regularly. This makes them ideal for applications where the motor must be continuously available to operate, is not easily accessible, or will operate without supervision for long periods of time.